package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheCilent;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheCilent cacheCilent;
    @Override
    public Result queryById(Long id) {
        // 缓存穿透
        // Shop shop = queryWithPassThrough(id);
//        cacheCilent.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById,
//                CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 互斥锁解决缓存穿透
        // Shop shop = queryWithMutex(id);

        // 逻辑过期解决缓存穿透
        // 提前存好了数据，一定存在数据
//        Shop shop = queryWithLogicExpire(id);


        Shop shop = cacheCilent.queryWithLogicExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById,
                CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if(shop == null) {
            return Result.fail("店铺不存在");

        }
        // 7. 返回
        return Result.ok(shop);

    }

    /**
     *
     * 已封装到CacheClient
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithLogicExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        // 1 从redis查询商城缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2 判断是否存在
        if(StrUtil.isBlank(shopJson)) {
            //3 不存在， 直接返回（说明不在预热的数据内，无需查询数据库）
            return null;
        }
        // 4 命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData(); // 不确定是什么对象，会自动转为jsonObject
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 5 判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            //5.1 未过期，直接返回店铺信息
            return shop;
        }


        //6 缓存重建
        //6.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取锁成果
        if(isLock) {
            //6.3 成功， 开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    // 重建缓存(但是此次重建后返回的还是旧的数据)
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    // 释放锁
                    unlock(lockKey);
                }

            });
        }
        //6.4 失败，返回商铺信息

        return shop;
    }

    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        // 1 从redis查询商城缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2 判断是否存在
        if(StrUtil.isNotBlank(shopJson)) {
            //3 存在， 直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        // 判断命中的是否是空值
        if(shopJson != null) {
            return null;
        }
        // 4 实现缓存重建
        // 4.1 获取互斥锁
        Shop shop = null;
        String lockKey = LOCK_SHOP_KEY + id;
        try {
            boolean isLock = tryLock(lockKey);
            // 4.2 判断是否获取成功
            if(!isLock) {
                // 4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            // 4.4 成功，根据ID查询数据
            shop = getById(id);
            // 模拟重建的延迟
            Thread.sleep(200);
            // 5 不存在， 返回错误
            if(shop == null) {
                // 将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6 存在，写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException();
        } finally {
            // 7.1 释放互斥锁
            unlock(lockKey);
        }

        // 8 返回
        return shop;
    }

    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        // 1 从redis查询商城缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2 判断是否存在
        if(StrUtil.isNotBlank(shopJson)) {
            //3 存在， 直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        // 判断命中的是否是空值
        if(shopJson != null) {
            return null;
        }
        //4 不存在，根据ID查询数据库
        Shop shop = getById(id);
        // 5 不存在， 返回错误
        if(shop == null) {
            // 将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6 存在，写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 7. 返回
        return shop;
    }


    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.MINUTES);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }


    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        // 1 查询店铺数据
        Shop shop = getById(id);
        // 2 封装逻辑过期时间
        RedisData redisData = new RedisData();
        Thread.sleep(200);
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3 写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

     */
    @Override
    // 加上事务, 是为了如果程序出错，则回滚数据库，redis是没有事务的
    @Transactional
    public Result update(Shop shop) {

        Long id = shop.getId();
        if(id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1 更新数据库
        updateById(shop);
        // 2 删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }
}
